With continued research into more energy-efficient compact fluorescents and light-emitting diodes, the halls of Berkeley and Vanderbilt are where you expect the latest breakthrough in lighting to occur today. Back in 1924, however, it was the military’s need to penetrate dark battle fields and unfriendly waters that drove advances in artificial lighting.

Engineers with the Navy were developing “monster searchlights” to help defend their cruisers and destroyers, PM reported in the February issue. “Visible at a distance of approximately 127 miles, the beam cast by the latest of these monster beacons is estimated at 500,000,000 candlepower,” PM wrote. The Navy tested the value of its behemoth searchlights in pursuit of stealth torpedo boats during battle exercises. “Restlessly searching the waves, one of the beams momentarily touched a dark object and passed on,” the cover story continued. “Almost instantly the phone rang—‘Destroyer on port quarter,’ was the report.” Still, fog presented an obstacle that even these lights couldn’t penetrate.

Today, more researchers favor exploring the possibilities of tiny LEDs than massive beams for illumination. And with fuel-based light costing an estimated $40 billion worldwide, it’s developing nations that could benefit most from the cheaper, cleaner, safer alternative of light-emitting diodes. Check back with PopularMechanics.com later this week for more ... —Emily Masamitsu